Ignoring "non-geometric" effects like depth of field, the only optical parameter that matters here is the visible angle (a function of focal length and crop fac

Ignoring "non-geometric" effects like depth of field, the only optical parameter that matters here is the visible angle (a function of focal length and crop factor). Parameters like the size of the aperture are massively important in general, but not for determining the relative size of objects within the scene.